Varela Ana R P, Gonçalves da Silva Amélia M P S, Fedorov Alexander, Futerman Anthony H, Prieto Manuel, Silva Liana C
Faculdade de Farmácia, Universidade de Lisboa, Lisboa, Portugal.
Biochim Biophys Acta. 2013 Mar;1828(3):1122-30. doi: 10.1016/j.bbamem.2012.11.018. Epub 2012 Nov 27.
Glucosylceramide (GlcCer), a relevant intermediate in the pathways of glycosphingolipid metabolism, plays key roles in the regulation of cell physiology. The molecular mechanisms by which GlcCer regulates cellular processes are unknown, but might involve changes in membrane biophysical properties and formation of lipid domains. In the present study, fluorescence spectroscopy, confocal microscopy and surface pressure-area (π-A) measurements were used to characterize the effect of GlcCer on the biophysical properties of model membranes. We show that C16:0-GlcCer has a high tendency to segregate into highly ordered gel domains and to increase the order of the fluid phase. Monolayer studies support the aggregation propensity of C16:0-GlcCer. π-A isotherms of single C16:0-GlcCer indicate that bilayer domains, or crystal-like structures, coexist within monolayer domains at the air-water interface. Mixtures with POPC exhibit partial miscibility with expansion of the mean molecular areas relative to the additive behavior of the components. Moreover, C16:0-GlcCer promotes morphological alterations in lipid vesicles leading to formation of flexible tubule-like structures that protrude from the fluid region of the bilayer. These results support the hypothesis that alterations in membrane biophysical properties induced by GlcCer might be involved in its mechanism of action.
葡萄糖神经酰胺（GlcCer）是糖鞘脂代谢途径中的一种相关中间体，在细胞生理调节中起关键作用。GlcCer调节细胞过程的分子机制尚不清楚，但可能涉及膜生物物理性质的变化和脂筏的形成。在本研究中，使用荧光光谱、共聚焦显微镜和表面压力-面积（π-A）测量来表征GlcCer对模型膜生物物理性质的影响。我们表明，C16:0-GlcCer具有高度倾向于分离成高度有序的凝胶域并增加液相的有序性。单层研究支持C16:0-GlcCer的聚集倾向。单一C16:0-GlcCer的π-A等温线表明，双层域或晶体状结构在气-水界面的单层域内共存。与POPC的混合物表现出部分互溶性，相对于各组分的加和行为，平均分子面积有所扩大。此外，C16:0-GlcCer促进脂质囊泡的形态改变，导致形成从双层流体区域突出的柔性管状结构。这些结果支持这样的假设，即GlcCer引起的膜生物物理性质的改变可能涉及其作用机制。
